Molybdenum, a promising metal for decontaminating water
UN/DICYT In Colombia only 30% of wastewaters are treated. Using solar photocatalysis, a chemical process in which the only source of energy is the sun, water quality could be improved. This method to eliminate organic compounds was used by UNal-Manizales Chemical Engineer Sandra Milena López Zamora, to search for the ideal material to help improve the photocatalytic properties of titanium dioxide (TiO2), very used in this type of procedures due to its high solar energy conversion efficiency.
Furthermore, says López, it is not toxic, is very stable and cheap, making it ideal for use in water decontamination techniques.
“In presence of light, titanium dioxide activates its catalytic effect producing a highly reactive compound which oxidizes wastewater organic compounds turning them into less polluting substances,” she said.
In this research project they synthesized and characterized titanium dioxide saturated with metals such as cobalt, iron, copper and molybdenum. The assessment of the first three demonstrated that they did not improve the activity of TiO2; on the contrary they diminished its catalytic activity.
However, molybdenum did improve the photocatalytic properties of titanium dioxide to breakdown polluted waters, especially when they have phenol, one of the compounds which impacts water the most. Phenol is a residue of industrial phenolic resin production and is used in foundry, coatings, filters, abrasives and adhesives, among others.
López says that the method of impregnating metals with titanium dioxide has been used previously, but the effects of molybdenum on phenol photo-breakdown had not been previously researched.
“The idea of impregnating titanium dioxide with molybdenum is to achieve complete mineralization (transformation of an organic compound into an inorganic compound) transforming the pollutant into carbon dioxide and water, biodegradables less contaminating for the environment,” said López.
Lopez carried out part of this project during an internship at the Lodz University of Technology in Poland by participating in the Intensified Reactive with Separation Processes and Advanced Materials Research Group (Prisma, for its Spanish acronym) headed by Professors Izabela Dobrosz Gómez and Miguel Ángel Gómez.
The need to preserve and treat water has increased interest in its reuse and recycling, especially in water streams polluted by chemical industries.